The great advocate for wilderness preservation wrote many letters extolling the wonders of Yosemite. His lyric, vividly written accounts describe sheep-herding, guiding visitors, and studying the region's diverse splendors. AUTHOR: John Muir (1838-1914) ranks among America's most important and influential naturalists and nature writers. Devoted to the preservation of wilderness areas, Muir founded the Sierra Club and was active in the establishment of Yosemite National Park.